An analog/digital conversion circuit (hereinafter also referred to as an AD conversion circuit) that converts an analog signal into a digital signal (hereinafter referred to as analog/digital conversion) generally has an amplification circuit that performs an amplifying operation.
However, this amplification circuit cannot provide a desired value as a gain in the amplifying operation due to a parasitic capacitance generated in the circuit or production variations, and deteriorates an accuracy of the AD conversion circuit in some cases.